Can Protein Shakes Make You Nauseous? (7 Reasons)

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There have been multiple reports of people feeling nauseous after drinking protein shakes. 

This Reddit user said they felt like “puking a couple of hours” after drinking whey protein

Another Reddit user said they used a vegetarian protein powder, and even 1 scoop made them feel nauseated to the point where they actually threw up.    

So, can protein shakes make you nauseous?  

Yes, protein shakes can make you nauseous. A low-quality protein or one that contains inulin fiber or artificial sweeteners can cause nausea. Drinking too much at once, drinking it too fast, or too close to your workout can be other factors. Nausea might also indicate a lactose or protein allergy more broadly. 

As the manager of a supplement store for the past ten years, one of the main parts of my job involves helping customers find a protein powder that they both enjoy and tolerate to help them achieve their results. 

Key Takeaways

I’ve Tested 22 Protein Powders, Find Out The Best Ones That DO NOT Upset Your Stomach

  • Nausea with protein shakes could be caused by the protein powder itself or the way you’re consuming it
  • Changing the timing of your shake, the brand of protein, or the type of protein can help relieve your nausea
  • Oftentimes nausea associated with protein shakes is a result of food intolerances that you may have been unaware of

What Are The Signs That Your Protein Shake Is Making You Nauseous? 

There are a few possible reactions you might have after taking protein powder that indicate it’s not the right product for you. 

If you experience gas, bloating, diarrhea, cramping, or general nausea after taking a protein powder, it’s time to manipulate how you are taking your protein, or consider switching powders altogether.

If you want to make sure that it’s your protein shake that is making you nauseous and not other factors throughout your day, have 1 scoop of your protein powder mixed with 6-8 ounces of water first thing in the morning. Drink it slowly over 5 to 10 minutes rather than all at once.  

If you experience negative symptoms like nausea, bloating, or gas after having only the protein shake with water, then it’s likely the protein powder itself that is the problem. 

If you don’t experience nausea after drinking your protein powder away from your workout, but you do experience nausea when taking your protein powder after the workout, then it’s probably the way you’re drinking it (e.g. drinking it too close to your workout, drinking it too quickly) and not the actual protein powder. 

  • Note: If you get diarrhea as a side effect, go to my other article on Protein Shakes & Diarrhea as there are some specific causes and fixes that go above and beyond simply feeling nauseous.  

7 Reasons Whey Protein Shakes Can Make You Nauseous 

7 reasons whey protein shakes can make you nauseous 

The 7 reasons that whey protein can make you nauseous are:

1. You’re Using a Low-Quality Protein

As consumers are becoming more educated, they are demanding more from supplement companies, which has been largely a good thing, requiring supplement companies to step up and produce higher-quality products. 

Unfortunately for protein powders, however, since they are considered a dietary supplement, they are not regulated by the Food and Drug Administration (FDA). This results in a wide disparity in the quality of protein supplements. 

A lesser quality protein will have more additives, fillers, or cheaper sources of whey that are higher in lactose and more likely to cause stomach upset. 

“If you have a sensitive gut, you need simple ingredients.”

Brittany Carpenter, MS, RDN/LDN

Here’s one of my top tricks for quickly identifying higher-quality protein powders: 

Take the total grams of protein per scoop, divided by the total grams of the scoop size then multiply by 100.

supplement facts

For instance, this product (Allmax Isoflex), offers 27g of protein per 30g scoop. 27 divided by 30 = 0.9 multiplied by 100 is 90. What this tells you is that the product is 90% protein per scoop.

Compare that to this whey protein from Six Star Nutrition:

whey protein from Six Star Nutrition

The scoop size is 47g, and it offers 30g of protein. 30 divided by 47 = 0.64 x 100 = 64. That means that for each scoop of this product that you take, only 64% of that scoop is protein. That leaves 36% of “other stuff” in your protein powder like sugar and additives.

Ideally, you want this number to be as close to 100 as possible. A protein powder with a protein percentage higher than 85% is an excellent quality product. One that falls between 75% and 85% is a good quality product. 

How To Fix

If you are shopping specifically for protein powder and not a meal replacement, then I would stay away from any powder with a ratio that falls below 75%.

If your protein powder does fall in the good to excellent categories, but still causes nausea or upset, check the list of non-medicinal ingredients. 

There should be very few ingredients here, limited mostly to the protein itself, and natural or artificial sources of flavor or color including cocoa, vanilla, stevia, sucralose, and beetroot powder.

2. Your Whey Protein Contains Inulin Fiber

Inulin is a type of soluble fiber found in plants that are sometimes added to food products to alter the texture or replace sugars and fats

While inulin fiber does generally offer a host of gut health benefits because it is a prebiotic fiber, which means it feeds the good bacteria in our gut, it can come with some negative side effects. 

The most common negative side effects of inulin fiber intake include gas, bloating, abdominal discomfort, and diarrhea or loose stool. 

How To Fix

Choose a protein powder that does not contain inulin fiber. You can find this by checking the non-medicinal ingredients and looking for the following items: inulin, oligofructose, chicory root, or chicory root extract.

3. Your Whey Protein Contains Artificial Sweetener

The three most common sweeteners you will find in protein powders include acesulfame potassium, sucralose, and stevia

In my research, I found a lot of anecdotal evidence about artificial sweeteners causing nausea or bloating, and I found a few incidences of doctors allegedly making these same claims, but I couldn’t find any peer-reviewed articles that demonstrated the same thing. 

The closest I came to a verifiable source was WebMD indicating that side effects of stevia include bloating and nausea. I did, however, find a lot correlating artificial sweeteners with migraines.

Sugar alcohols, on the other hand, like erythritol, maltitol, and xylitol, are known to be more likely to cause symptoms of nausea and GI upset. 

This all being said, I cannot dismiss the hundreds of conversations I have had in my ten years managing a supplement store. I have heard first-hand stories of customers relaying their experiences with negative stomach reactions to sucralose or stevia. 

It’s possible that the type of sweetener used, or the high level of sweetness (most of these artificial sweeteners are hundreds of times sweeter than table sugar) can be contributing to nausea. 

How To Fix

If you have tried the other fixes listed here and are still experiencing nausea, try a product that is sweetened differently. If your current product uses sucralose, try one that is stevia-based or vice-versa. 

Some companies, like Beyond Yourself, will use a blend of stevia and sucralose to try to mitigate the symptoms associated with taking too much of either.

If changing protein powders doesn’t help the problem, try a completely unflavoured protein powder (like a whey powder from Naked Nutrition). 

4. You’re Taking Too Much Protein at Once

Old conventional wisdom had us all believing that our bodies couldn’t absorb more than 25-30 grams of protein at one time. 

In recent years, that’s been proven untrue, but does that mean you should start double scooping your protein shakes? Not necessarily. 

The body is really good at self-regulating, especially where amino acid absorption is concerned. The majority of amino acids are digested in the small intestines, which can hold and store a lot of amino acids until the body needs them. 

However, some enzymes are needed in the stomach and small intestines to break down the protein into these amino acids. If too much protein is consumed in one sitting, the digestive system might not be able to keep up with the demand of enzymes required for digestion. 

Until the body catches up on enzyme production, you could be left with a feeling of indigestion or nausea.

How To Fix

The current standard for protein intake for optimal muscle gain is 1.6g of protein per kg of body weight per day, distributed over four meals. This translates to consuming 0.4g of protein per kg of body weight per meal. 

For a 200lb individual, this translates to around 36g of protein per serving. 

To minimize the likelihood of too much protein causing nausea, find your ideal grams of protein per serving and stay at or below that level.

Remember that you are not obligated to use the exact scoop size of your product. If your protein offers 25g per scoop and your ideal serving size is 36g, you can do 1 ⅓ scoop to get you close to that amount. 

5. You’re Drinking Your Protein Shake Too Quickly

Drinking your protein shake too quickly could be contributing to your nausea. This isn’t reserved just for protein shakes; consuming too much of anything too quickly can cause gastric upset.

“If you’re feeling nauseous from a protein shake outside of a post-workout scenario, it may be caused by drinking the shake too quickly”

Steve Hertzler, Ph.D., R.D

Chugging your drink too fast can result in you swallowing more air which can cause bloating and gassiness. 

If you drank a pre-workout and/or consumed water during your workout, you could already have a reasonably large volume of water sitting in your stomach. Slamming a protein shake quickly can rapidly add to that existing volume, resulting in nausea. 

How To Fix

Take your time. Sip on your protein shake over several minutes rather than chugging it in one go. 

As an added tip, make sure to mix your protein shake with around 6-8oz of water rather than filling your entire shaker cup to minimize the extra volume load in the stomach.

6. You’re Drinking Your Protein Shake Too Close to Your Workout

As you work out, the body focuses on getting blood to your muscles and lungs and focuses less on digestion. Slamming your protein shake too close to your workout before the body is ready to digest it can lead to nausea and upset stomach. 

Old school wisdom had us believe that there was a very narrow post-workout window to consume protein to gain muscle. This resulted in people throwing back protein shakes as quickly as they could post-workout. 

The reality is, muscles are sensitized to protein intake for up to 24 hours post-workout, so the anabolic window isn’t as narrow as we initially thought. Research is indicating that the most important thing is getting adequate protein throughout the day, regardless of timing. 

How To Fix

Have your protein shake approx 30 minutes after your workout. 

Take time to properly cool down, get changed, and then enjoy your shake. 

7. You Have a Lactose Intolerance You Didn’t Know About

Lactose intolerance is defined by the inability to digest the sugar that is naturally found in milk products (called lactose). This typically occurs when the small intestine does not produce the enzyme lactase which is required to break down lactose.

The side effects of lactose intolerance include gas, bloating, diarrhea, or nausea which can appear anywhere between 30 minutes and 2 hours after consuming lactose. 

It is estimated that approximately 30 million American adults have some degree of lactose intolerance. 

It is also possible to be reactive to casein protein, specifically. Casein is a protein found in milk that gives it its white color, and it tends to be more problematic to digestion than whey and vegan proteins. 

How To Fix

The most definitive way to find out if you have a lactose or milk protein allergy will be to get a diagnostic test done by a doctor. 

In the meantime, however, there are some ways that you can experiment to find a protein formula that suits you. 

For suspected lactose sensitivity: Choose a whey isolate or whey hydrolysate that has 0g of sugar on the ingredient list. Since lactose is a milk sugar, a formula that has no sugar in it should be virtually lactose-free. 

For a suspected milk protein allergy: Choose a vegan or animal-based (beef, salmon, egg) protein powder. 

If you love your protein powder and are reluctant to change, you could consider adding a digestive enzyme supplement. 

A product like Allmax Digestive Enzymes includes protease (an enzyme to break down protein) and lactase, which might help you better digest your protein and eliminate gastrointestinal symptoms.

Choosing A Whey Protein That Doesn’t Make You Nauseous

1. Dymatize ISo100

One of my favorite whey proteins is Dymatize Iso100 (click to read my review)

It has been filtered to remove the excess lactose, offers around 85% protein per scoop, and tastes great. 

It boasts a 4.7/5 rating on Amazon, based on over 19,000 ratings with many mentioning its great taste and easy digestibility.

2. Vega Sport Protein

If you want to avoid whey protein altogether, Vega Sport Protein powder offers one of the highest overall grams of protein per scoop (30g) and sits at 68% protein per scoop. 

It’s rated at 4.5/5 on over 10,000 Amazon ratings and is certified safe for tested athletes and gluten-free.

What To Do If You Still Get Sick After Implementing These Tips

If you have tried finding a lactose-free or vegan formula and adapting the timing of your protein intake, then it’s possible that a protein powder supplement simply isn’t the right avenue for you. 

Instead, try a food-based meal or protein supplement post-workout. 

Some examples include

  • Tuna 
  • Hard-boiled eggs
  • Greek yogurt or cottage cheese

If you still want the convenience of a grab-and-go snack, try a protein bar like Grenade Bars or Iron Vegan Bars.

Want more ideas?  Check out my article on 15 Post Workout Alternatives To Whey.

Other Side Effects of Protein Powder

Frequently Asked Questions

How Common Is It For People To Get Sick After Drinking Whey Protein?

It is relatively common for people to get nauseous after drinking whey protein, because it can happen for a lot of reasons. It could be due to the protein itself (low quality, artificial sweeteners, added fiber, milk allergy) or due to how you’re drinking protein (too much, too fast, or too soon after a workout).

If I Get Nauseous After Drinking Whey Protein Does The Protein Go To Waste?

While getting nauseous can be irritating and uncomfortable, your protein hasn’t gone to waste if you get nauseous. As long as you do not throw up the protein, it will be digested and broken down into the amino acids necessary for recovery and muscle growth. 

Can Drinking Too Much Protein Make You Nauseous?

Yes, drinking too much protein can make you nauseous. Consuming too much protein in one serving (more than 50g), or drinking it too quickly or with too much water can all lead to nausea. Mix 20-40g of protein with 6-8oz of water, and sip on it over the course of several minutes to reduce the likelihood of nausea.

Can Protein Powder Make You Throw Up? 

Protein powder could make you throw up, especially if you have a sensitive stomach. If protein powder continues to make you nauseous to the point that you’re being sick then you should try changing brands, types, or forgo it altogether.


Shoaib, M., Shehzad, A., Omar, M., Rakha, A., Raza, H., Sharif, H.R., Shakeel, A., Ansari, A., & Niazi, S. (2016). Inulin: Properties, health benefits, and food applications. Carbohydrate Polymers, 147, 444-454.

Patel, R.M., Sarma, R., & Grimsley, E. (2006). Popular Sweetener Sucralose as a Migraine Trigger. Headache: The Journal of Head and Face Pain, 46(9), 1470.

Storey D, Lee A, Bornet F, Brouns F. Gastrointestinal tolerance of erythritol and xylitol ingested in a liquid. Eur J Clin Nutr. 2007 Mar;61(3):349-54. doi: 10.1038/sj.ejcn.1602532. Epub 2006 Sep 20. PMID: 16988647.

Schoenfeld, B. J., & Aragon, A. A. (2018). How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. Journal of the International Society of Sports Nutrition, 15, 10.

Schoenfeld, B.J., Aragon, A.A. & Krieger, J.W. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr 10, 53 (2013).

About The Author

Jennifer Vibert

Jennifer Vibert is a Certified Strength and Conditioning Specialist, Nutrition Coach, and supplement store manager. She has a Bachelor of Kinesiology with a major in Fitness and Lifestyle and a minor in Psychology from the University of Regina. She is a Certified Nutrition Coach through Precision Nutrition, with a passion for helping clients learn the fundamentals of nutrition and supplementation in order to build healthy, sustainable habits.

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